org.eclipse.sisu.bean.DeclaredMembers Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2010-present Sonatype, Inc.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Stuart McCulloch (Sonatype, Inc.) - initial API and implementation
*******************************************************************************/
package org.eclipse.sisu.bean;
import java.lang.reflect.Member;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* {@link Iterable} that iterates over declared members of a class hierarchy.
*/
public final class DeclaredMembers
implements Iterable
{
// ----------------------------------------------------------------------
// Implementation fields
// ----------------------------------------------------------------------
private final Class clazz;
private final View[] views;
// ----------------------------------------------------------------------
// Constructors
// ----------------------------------------------------------------------
public DeclaredMembers( final Class clazz, final View... views )
{
this.clazz = clazz;
this.views = views.length == 0 ? View.values() : views;
}
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
public Iterator iterator()
{
return new MemberIterator( clazz, views );
}
// ----------------------------------------------------------------------
// Implementation types
// ----------------------------------------------------------------------
/**
* Read-only {@link Iterator} that uses rolling {@link View}s to traverse the different members.
*/
private static final class MemberIterator
implements Iterator
{
// ----------------------------------------------------------------------
// Constants
// ----------------------------------------------------------------------
private static final Member[] NO_MEMBERS = {};
// ----------------------------------------------------------------------
// Implementation fields
// ----------------------------------------------------------------------
private Class clazz;
private final View[] views;
private int viewIndex;
private Member[] members = NO_MEMBERS;
private int memberIndex;
// ----------------------------------------------------------------------
// Constructors
// ----------------------------------------------------------------------
MemberIterator( final Class clazz, final View[] views ) // NOPMD
{
this.clazz = clazz;
this.views = views;
}
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
public boolean hasNext()
{
while ( memberIndex <= 0 )
{
if ( viewIndex >= views.length )
{
// reset view
clazz = clazz.getSuperclass();
viewIndex = 0;
}
if ( null == clazz || clazz == java.lang.Object.class )
{
return false;
}
final int index = viewIndex++;
members = views[index].members( clazz );
memberIndex = members.length;
}
return true;
}
public Member next()
{
if ( hasNext() )
{
// initialized by hasNext()
return members[--memberIndex];
}
throw new NoSuchElementException();
}
public void remove()
{
throw new UnsupportedOperationException();
}
}
/**
* {@link Enum} implementation that provides different views of a class's members.
*/
public static enum View
{
CONSTRUCTORS
{
@Override
Member[] members( final Class clazz )
{
return clazz.getDeclaredConstructors();
}
},
METHODS
{
@Override
Member[] members( final Class clazz )
{
return clazz.getDeclaredMethods();
}
},
FIELDS
{
@Override
Member[] members( final Class clazz )
{
return clazz.getDeclaredFields();
}
};
abstract Member[] members( final Class clazz );
}
}